1. Field of the Invention
The present invention relates to a measuring timer system for measuring the period of input pulse signals, particularly measurement of a slight error of the period when the period value is roughly estimated.
2. Description of the Prior Art
FIG. 3 shows a circuit block diagram of an existing measuring timer system for measuring the period of input pulse signals. In FIG. 3, numeral 1 is a timer for measuring the period of input pulse signals, 2 is a measurement result register for holding measurement results, and 1S is a switch.
FIG. 4 shows the timing for measurement.
The following is the description of operation. When the input pulse signal changes (point "a" in FIG. 4) (detected at the leading edge of the input pulse signal), the timer 1 is reset start counting from the initial value. When the input pulse signal changes next (point "b" in FIG. 4), the switch 1S is turned on to hold the then counted value as a measurement result before resetting the timer 1. The above operation is repeated every input pulse signal period.
A slight error may occur in the period of the input pulse signal. In this case, the error can accurately be measured by increasing the clock speed.